A nonwoven fabric is formed into a strip, then is wound up in the form of a roll for storage. When next using the nonwoven fabric, the nonwoven fabric is unwound from the roll. The nonwoven fabric is, for example, used as a component member such as a top sheet of an absorbent product such as a disposable diaper or sanitary napkin.
In this regard, if the nonwoven fabric is wound up in the form of a roll, the nonwoven fabric will be compressed in the thickness direction and the nonwoven fabric will be liable to be reduced in bulk or thickness. If the nonwoven fabric is reduced in bulk, the nonwoven fabric is liable to fall in speed of liquid absorption or fall in flexibility.
On the other hand, if heating the nonwoven fabric, the nonwoven fabric which was deformed by compression will be returned to the original state in terms the fiber and the bulk of the nonwoven fabric will be restored.
Therefore, there is known a method of blowing hot air on to nonwoven fabric to restore bulk of the nonwoven fabric (see PLT 1). In this method, the hot air is blown vertical to one surface of the nonwoven fabric.
Further, there is also known another method for restoring bulk of a nonwoven fabric comprising making the nonwoven fabric snake so as to proceed alternately in a mutually opposite first direction and second direction while supplying hot air in a second direction (see PLT 2, FIG. 6).